“地壳异常压力”学术研讨会

A SEMINAR ON ANOMALOUS PRESSURE IN THE CRUST

延用至今的地质作用深度测算方法 ,即重力 /密度法 ,是基于“地下岩石处于静水压力状态” (Heim,1978)和“地下某一深处的垂直压力等于上覆岩石柱的总重量” (ДИННИК,1937)两个理论假设。下面刊登的是“地壳异常压力学术研讨会”专家们的发言 (北京 ,2 0 0 0 . 2 )。到会专家对上述假设和测算方法提出了不同见解 ,指出 ,浅部地壳直至地幔深处的岩石都是固体状态 ,地下的压力是极不均匀的 ,所以对地壳中的地质作用深度的测算必须把所处岩石看作固体 ,并依据固体物理理论 ,也就是说 ,除重力之外 ,构造力、瞬时压力、结晶力、变质作用、岩石相变等都会产生局部巨大的异常压力。因此 ,应该对地壳异常压力进行深入研究以建立更具普适性的深度测算公式。专家们还认为 ,对在全球具有重要地位的大别超高压变质带的形成深度 ,我国科学家认为是 32 km左右 ,属壳内成因 ,并提供了测算数据 ,但该项研究还应深化。

Papers collected in this volume are focusing on anomalous pressures present in the crust. Some theoretical considerations and calculations of pressures at certain depths are proposed.\;The pressure depth relation can generally be obtained from a certain density depth distributaion in the region. It is known from stress measurements that the horizontal stress is almost always great than the vertical stress. This indicates that tectonic stress may play some important role in the stress state.\;Furthermore,some other additional stresses may also be generated by facies changes,metamorphism,crystallization in the crust. How the UHPM rocks now exposed at the surface were formed is open to discussion. Lu et at (1988) proposed a method for determination of pressure at some depth.